Adjectives decline according to the grammatical gender and number of the nouns they modify.
hvid - singular common gender.
hvidt - singular neuter gender.
hvide - plural of either gender.
hvide is also used when applied attributively (in front of) a definite noun, as in “det hvide brød”.
there is defiantly something wrong with that bread (I have never seen white bread before)
Definitely* also there's brown and white bread lol. I think I even saw green bread once!
I understood that what you say is for the definite way (det hvide brod). here it's used with "er", so it is an attribute (at least, we call it that way in French). With "er" it's the simple way (common or neutral).